1. Technical Field
The present invention relates to a liquid ejecting head which ejects liquid from a nozzle opening, a liquid ejecting head unit and a liquid ejecting apparatus.
2. Related Art
An ink jet-type printing head, which is a representative example of a liquid ejecting head for ejecting liquid droplets, includes for example a channel-forming substrate having a pressure generating chamber, and a piezoelectric element installed at one surface of the channel-forming substrate, and the ink jet-type printing head creates pressure in the pressure generating chamber by means of displacement of the piezoelectric element. The ink jet-type printing head may eject ink droplets through a nozzle opening.
Also, two reservoirs commonly communicated with a plurality of pressure generating chambers may be provided such that ink may be supplied from an ink tank to the two reservoirs (e.g., see Japanese Patent No. 3097321).
Further, there is also provided an ink jet-type printing head, which has a liquid channel in the head for flowing a warm water in an installation direction of the pressure generating chambers such that the ink in each of the pressure generating chambers is heated by the warm water flowing in the liquid channel in the head (e.g., see JP-A-2008-55716).
By using this, the ink in the pressure generating chamber is heated to decrease viscosity, thereby improving ink discharging characteristics.
However, in Japanese Patent No. 3097321, just two reservoirs are provided, but the ink in the pressure generating chamber is not heated, the ink in two reservoirs are not circulated, and also it is impossible to discharge ink with desired ink discharging characteristics.
In addition, where only the liquid channel in the head is provided to flow warm water in the installation direction of the pressure generating chambers as in JP-A-2008-55716, the heating temperature is not uniform at both ends of the pressure generating chambers in an installation direction but generates a temperature gradient, so variation occurs in the discharging characteristics of the ink discharged from each nozzle opening, thereby deteriorating the printing quality.
Further, it is substantially not easy to provide a heating unit to every channel of the pressure generating chambers or the like, and the ink near the nozzle opening is insufficiently heated, so it is impossible to discharge a sufficiently heated ink with excellent discharging characteristics.
In addition, such problems occur not only in the ink jet-type printing head but also in a liquid ejecting head that ejects liquid other than ink.